Various types of tap chucking means have been previously employed for tapping work to a predetermined depth. These prior devices incorporate clutch mechanism to automatically stop tap rotation while allowing the spindle to rotate continuously when tapping work to a predetermined depth is completed. All of these prior devices, however, have a complicated construction and have many limitations in handling. Further, various parts must be exchanged with others in order to adjust the tapping depth so that these prior tapping means are often quite impractical.